System for testing pulse generators



D. H. BEAL ETAL SYSTEM FOR TESTING PULSE GENERATORS April 16, 1957 2Shets-Sheet l Filed May 26, 1953 April 16, 1957 D. H. BEAL ETAL SYSTEMFOR TESTING PULSE GENERATORS Filed May 26, 1953 TIME O ff) NME 2Sheeis-Sheet 2 COMPARATOR AND LEVEL SEL.

D. M. Z/NNVY BY z Z l l m Arm/ver United States Patent SYSTEM FonTESTING PULSE GnNnnArons Dick H. Beal, Western Springs, El., Richard C.Pomeroy, Qnakertown, Pa., and Gordon H. Robertson, La Grange Park, andDaniel M. Zinn, Elgin, 1li., assignors to Bell Telephone Laboratories,Incorporated, New York, N. Y., a corporation of New York Application May26, 1953, Serial No. 357,594

Claims. (Cl. 324-57) This invention relates to testing equipment andmore particularly to systems for testing or monitoring the operatingcharacteristics of an electrical device such as a pulse generator.

A need arises in testing and experimenting with oscillators, pulsegenerators, and the like, to measure the reliability of operation of thedevice under observation. The oscillations or pulses generated may varyin amplitude, duration, or repetition frequency and it may be desired toascertain, over a period of a substantial number of pulses, whatproportion of the pulses satisfy arbitrary requirements as to minimumamplitude, duration, and uniformity of spacing, etc. rThe source of theoscillations or pulses may be of the externally excited type, in whichcase the number of input pulses delivered to the source and the numberof satisfactory output pulses may each be counted and the countscompared to determine, for example, the percentage of pulses that aremissing or that do not meet the standard requirements.

In accordance with the invention, two pulse counting mechanisms areemployed, each operating to count the number of pulses in one of thetrains of pulses to be compared. One counting mechanism counts forwardin the usual manner from a low initial number to a higher final number.The other counting mechanism may be forward counting or it may have itscounting indicator arranged to count backward, i. e. from a high initialnumber to a lower nal number. To measure the percentage of missing andsubstandard output pulses compared to the number of input pulses, theforward counting indicator is set to begin at zero and count to aselected number, which may conveniently be an integral power of ten,such as l0, 100, 1000, 1,000,000, etc. 1n the case of backward countingthe indicator is set to begin at the number selected for the final countof the forward counting device. When an integral power of ten is soselected, the nal reading of the backward counting indicator gives thedesired percentage of missing pulses directly except for the position ofthe decimal point, which may be readily determined in a given case ormay be shown automatically under control of a selective device whichdetermines the nal reading of the forward counting indicator.

The system of the invention is not coniined in its usefulness toindicating the percentage of missing pulses in a selected number ofpossible pulses, but the system may be used to count the input pulsesand the number of missing or substandard pulses Within a measured timeinterval. The'usefulness of the system is not limited to counting inputand output pulses under circumstances Where output pulses occursubstantially simultaneously with the co1'- responding input pulses, itbeing possible to stop the application of input pulses to the source atany desired number and to permit the system to count output pulses overas long a period as may be required to include all the resulting outputpulses.

In accordance with the invention, one or more selective devices areinterposed between the source and the backward counting device todistinguish between standard and ice substandard output pulses. Suchselective devices may be omitted if it is desired to count all outputpulses that are able to actuate the counter and to register the number0f pulses that are missing as distinguished from the number that areeither missing or substandard.

In the drawings:

Fig. 1 is a block diagram of a system in accordance With the invention;

Figs. 2 and 3 are block diagrams showing alternative arrangements for aportion of the system shown in Fig. 1;

Fig. 4 is a schematic diagram of a suitable integrator and amplifier,and Fig. 5 is a schematic diagram of a comparator and level selector,for use as component parts of systems according to Figs. 1, 2, and 3;

Fig. 6 is a graphical representation of an input pulse train in acomparator as shown in Fig. 5;

Fig. 7 is a graphical representation of the output pulse train in thecomparator of Fig. 5 corresponding to the input pulse train of Fig. 6;

Fig. 8 is a schematic diagram of an anticoincidence gate; Fig. 9 is aschematic diagram of a forward counting pulse counter; Fig. 10, of abackward counting pulse counter; and

Fig. 11, of a calibrator; for use as component parts of systemsaccording to Figs. l, 2, and 3.

Referring to Fig. l, an oscillator 10 or other generating device undertest is arranged to be controlled or pulsed by a puiser 11. The outputcircuit of the oscillator is connected to a frequency selector 12through an attenuator 1?. From the frequency selector there extends atrain of apparatus elements consisting of a rectifier 14, an integrator(and amplifier) 15, a comparator (and level control) 16, and a pulseregenerator 17. A similar pulse regenerator 18 is arranged to be pulsedby the puiser 11 simultaneously with the oscillator 10.

An output pulse counter 19 is connected to the output circuit of thepulse regenerator 17 and an input pulse counter 20 is connected to theoutput circuit of the pulse regenerator 13. The output pulse counter isso named because its function is to count pulses coming from the outputcircuit of the oscillator 10, While the input pulse counter is so namedbecause it counts pulses impressed by the pulser 11 upon the inputcircuit of the oscillator 10. A starter 21 is provided for starting thecounting operation of the input pulse counter 20, which latter isconnected to the output pulse counter 19 for the transmission of astarting impulse to the latter. The counter 20 has another connection tothe counter 19 for the transmission of a stopping impulse to the latter.

The operation of the arrangement of Fig. 1 is as follows. The pulser 11intermittently energizes the oscillator 10 causing the latter togenerate trains or pulses of oscillations in well known manner. Theenergizing impulse impressed upon the oscillator by the puiser is calledan input pulse and the train of oscillations generated by the oscillatoras a result of an input pulse is called an output pulse as hereinaboveexplained. The output pulse may be adjusted in amplitude as desired bymeans of the attenuator 13.

ln accordance with a feature of the invention each output pulse issubjected to one or more tests to determine whether or not it shall becounted. The trst test applied is a check of the frequency of theoscillations making up the output pulse. In the case of a magnetronoscillator it is known that the magnetron is capable of oscillation inmore than one mode, each mode in general being characterized by adifferent frequency. The frequency selector 12 is arranged to pass theoutput pulse if the oscillations comprising the pulse are of thefrequency of the desired mode, for example, the frequency of thecommonly employed 1r-mode. if the pulse is of the Wrong frequency it isnot passed through the selector.

Pulses that pass the selector 12 are rectified by the rectier 14 toobtain a rectified current pulse that has substantially the same shapeas the envelope of the unrectifed input pulse.

to the area of the pulse. More particularly, the integrator f produces'a short pulse the height of which is proportional to the area of theincoming rectified pulse. As much amplication may be introduced in .theintegrator as necessary to develop a pulse of suflicient power `foi`further use in the remainder of the train of apparatus leading toV theoutput Vpulse counter.

The comparator 16 performs a continual measurement The energy of theoutput pulse, is proper-- tional to the area under the envelope of theoutput pulse,

of the height of the pulses from the integrator and com- Y pares theheight of an occasional short pulse with the average height of a numberof immediately preceding pulses. The comparator is set to reject anypulse that falls 'belows a designated percentage-of the average heightso that such a deficient pulse will not operate the output pulsecounter.

The pulse regenerators 17 and 18 are used when needed to insure pulsesof desired shape, such for example as to produce reliable operation ofthe counters, and more particularly for'providing input pulses andoutput pulses of identical shape when as in the system to be describedin connection with Fig. 3 operation of the output pulse counter isconditioned upon coincidence or anticoincidence Vbetween input "andoutput pulses.

The counters 19 and 20 countoutput pulses and input pulses respectively.The Vinput pulse counter is started in operation by means of the starter21 'and the input pulse counter'in turn passes a signal to the outputpulse counter' which starts the latter substantially simultaneously withthe input pulse counter. The input pulse counter may be adjusted tocount to any desired number, conveniently an integral power of ten, andthen to shut itself -off and pass a signal to the output pulse counterthereby shutting off the latter. The'scale on the :output pulse countermaybe reversed so thatthe counter will count backward and thus en'd upwith a iinal count that is the Ydifference between the number of inputpulses and thernumber of output pulses. Where theinput count is anintegral powerof ten,

the percentage of missingor defective pulses may be read directly fromthe scale of the output pulse counter.

In the arrangement of Fig. 2, a timing mechanism 22 is inserted betweenthe starter 21 and the input pulse counter 20. The number 'of missingpulses in a given'period of time may be ascertained by means of thisarrangement, andthe percentage of missing pulses in the same period oftime may be calculated. The'starter`21Y causes a starting -signal to besent to the input pulse counter which in turn'sends a starting signal'tothe'output 'pulse counter. At the end of the `predetermined period oftime for which the timer 22 is adjusted, the timer sends a stoppingsignal tothe'inputpulse counter which in turn sends a stopping signal'tothe output pulse counter. Y

YWhile in the arrangements of Figs. l and 2', the output pulse counteris actuated in turn by each output pulse that passes the tests set up bymeans of the frequency selector 12 and the comparator 16, in thearrangement'of Fig. 3, the counter 19 is actuated only when a pulsefails to pass the requirementsof the testing devices. For 'this purposean-anticoincidence' gate y23 isconnected tothe output circuits of therespective pulse regenerators Y17 and 18. The pulse regenerator kI'S isleft vconnected 'to ltheinput pulse counter 2t? but the pulseregenerator 17 is no longer directly connected to the output pulsecounter 19.

In the operation of the arrangement of Fig. 3, whenever an output pulseappears at the output of the pulse regenerator 17 it is matched by asubstantially identical input pulse at the output of the pulseregenerator 18. These substantially identical pulses are compared in theanticoincidence circuit 23 and as a result no signal is passed to thecounter 19 and the counter is not actuated. When, however, there is nooutput pulse to olfset a given input pulse, the circuit 23 passes asignal to the counter 19 and the counter registers one unit. As in thecase of the arrange-V ments of Figs. l and 2, when the starter 21 isactuated, a starting signal is passed to the input pulse counter 20which in turn passes a starting signal to theroutput pulse counter 2t?,empowering the latter counter to start counting any signals which maypass the anticoincidence gate 23. When the input pulse counter hasreached its predetermined count it shuts itself Cif and sends a stoppingsignal to the output pulse counter thereby disabling the lat-Y ter fromfurther counting. As before, the percentage of missingV pulses may beread off from the dial of the counter 19 as in the case Vof thearrangements of Figs. l and 2. Here the counter 19 is arranged to countforward in the Yusual manner.

Resetting means for restoring the counters to the proper initialreadings may be provided as is well known in the art of countingdevices. in the case of backward counting in the output pulse counter19, the initial setting will be to the same `number as the predeterminedfinal reading of the input pulse counter 26, so that the counter 19 willindicate the number of missing and defective pulses.

A calibrator Z4 is vshown in Fig. .1, and may be connected to the systemwhen needed by means of two single pore double throw switches 25 and 26,hy placing switch 25 in the downward position and switch 26 in theupward position. The calibrator provides two inputs, one consisting Vofa train of pulses Va fixed proportion of which are missing and the otherconsisting of anV unbroken `train of triggering pulses. The pulse trainwith missing pulses is impressed upon the input terminals of thecamparator 16 in place of the pulse train from the integrator 15. Thetriggering pulses are impressed upon the pulse regenerator 'in' lieu oftriggering pulses from the pulser 11. To restore the system to normaloperation after calibration,

Y the switch 2S is thrown to the upward position and the tions havingfrequencies inthe usual microwave range.V

The magnetron lmay have either coaxial cable output, wave guide outputor other suitable output facilities. T he pulser 11 may be of anyconventional kind for. generating suitable triggering pulses foractivating the magnetron in intermittentmanner as is common in practice.

The frequency selector 12 for usewith a magnetron may be any known typeof wave meter of the through transmission type, such for example as acavity resonator with input and Voutput aperturesfor wave guideinstallation, or with'input and output probes for coaiiialfcableinstallation.V 'The attenuator V13 maybe of any of the types-known Vto'the art which are adapted foruse inthe frequency vrange oftheoscillator. The rectifier 14 may be acrystal and maybe mountedinside awave guide .or coaxial cable in accordance with known practice.

Fig. 4 shows the `details of 'a suitable circuit for the integrator 15.Three 4stages of spacedischarge.circuits are Y showninorderto provide-suitable amplification and isolation between the rectierand theintegratingcircuit as well 'as between the integrating circuit andthecomparator 16. The first stage is a pentode 27 furictioning as aWideband amplifier such as is commonly employed in video amplifyingsystems. This stage is capable of amplifying the pulses formed by therectifier 14 with small or negligible distortion of the wave form of thepulses. Hence, if the rectifier faithfully reproduces the envelope shapeof Ithe high frequency pulses from the magnetron, the envelope form willagain be faithfully reproduced in the output pulse from the pentode 27.

The second stage of the integrator 15 is a triode 28 functioning inconventional manner as a cathode follower, reproducing the pulse fromthe pentode 27 in its cathode resistor 29. The integrator properconsists of a series combination of a resistor 3i) and capacitor 31which constitute the R and C respectively of a conventional RCintegrating circuit wherein the potential of the rapacitor follows theintegrated value of the pulse in the cathode resistor. The finalpotential reached by the capacitor 31 when the impressed pulseterminates is a measure of the area of the pulse and hence of the areaunder the venvelope of the high frequency pulse impressed upon therectifier 14. The potential of the capacitor 31 falls off exponentiallythereafter at a rate determined by the product RC as is well known, andthe capacitor should be substantially discharged by the time thesucceeding pulse arrives.

The third stage of the integrator 15 is a triode 32 which functions inknown manner to amplify the height of the pulse impressed upon its gridfrom the capacitor 31. This stage is not required to preserve the waveform of the impressed pulse but it is merely required to provide linearamplification of the height of maximum potential of the pulse. Theoutput of this stage therefor provides a pulse the height of which isagain a measure of the area under the envelope of the high frequencypulse and of increased amplitude as may be required to insure reliableoperation of the comparator 16.

Fig. 5 shows details of a circuit suitable for the comparator 16. Itcomprises two space discharge devices having their anode and cathodecircuits connected in parallel to each other with respect to the anodecurrent supply circuit and having their control grids directly connectedtogether. The space discharge devices may be the two halves of a twintriode tube. One triode, designated 33, functions as a cathode followerpresenting to incoming pulses a high impedance in the control grid pathand reproducing the pulses in a low impedance ci-rcuit comprising thecathode resistor 34. The other triode 35 is provided with an RC cathodepath comprising a potentiometer 36 and a capacitor 37. The time constantof the RC network 36-37 is made suiciently large so that wt en thecapacitor 37 is charged to the full potential of the received pulses,the capacitor will retain the charge with negligible leakage through thepotentiometer 36 over a period of missing pulses of a duration which isthe maximum period to be expected in using the device. ln the embodimenttested the time constant was sufficiently large to take care of asuccession of missing pulses. On the other hand, if the magnetron istunable and its output power is a function of the frequency generated,the potential in the network 36-37 will adjust to a new value after apredetermined time such as a few seconds, thereby making the deviceconveniently adaptable to variable power conditions. The slider 38 ofthe potentiometer 36 may be used to select any desired portion of thefull potential of the potentiometer for comparison with the pulse in`the resistor 34. The potentials thus to be compared are opposed to eachother in a series circuit comprising the resistor 34, the portion of thepotentiometer between the slider 38 and ground 39, and a unidirectionalconductor shown as a diode 4t). The potential across the selectedportion of the potentiometer constitutes 'a biasing potential for thediode 4d, the positive potential of the slider 3S of the potentiometerbeing impressed upon the cathode ofthe diode. The biasing potential 6blocks current from passing through the diode unless and until thebiasing potential is exceeded by the potential developed across theresistor 34 during the transmission of a pulse. Thus it is only theportion of the pulse that eX- ceeds vthe biasing potential that ispassed to the pulse regenerator 17 by the comparator i6.

Illustrative representations of input pulses and output pulses in thecomparator 16 are shown in Figs. 6 and 7 respectively for `the casewhere the slider 38 is adjusted to select 70 percent of the maximumamplitude of the in'- put pulse. By moving the slider 38 along thepotentiometer 36 other percentages may be selected and the potentiometermay be calibrated in known manner to indicate the proper position of theslider for the desired percentage. The function of the comparator may bedescribed as that of a proportional amplitude discriminator.

The device of Fig. 5 is disclosed and claimed per se by R. C. Pomeroy,one of the joint applicants herein, in a copending sole application forProportional Amplitude Discriminator, Serial No. 361,233, led June l2,1953. t

The pulse regenerators 17 and 18 may be conventional triggeredmultivibrators. While these components may be omitted if desired, theirinclusion is generally advantageous. One function of these components isto produce an output pulse of uniform shape and size for each inputpulse applied, thus insuring reliable operation of the counters 19 and2t). Another function is to provide substantially identical pulses forcomparison in the anticoincidence gate 23, since comparison ofdissimilar pulses is unsatisfactory and conducive to error.

Fig. 8 shows details of a suitable anticoincidence device for use as thegate 23 in the system of Fig. 3. A pentode 41 has two input circuits,one rconnected to the outermost grid electrode 42 and the otherconnected to the innermost grid electrode 43. A screening electrode 44is positioned between the grids 42 .and 43.l The pentode will not pass apulse unless grids 42 and 43 are both biased to proper potentials. Forthe purposes of the gate 23, a pulse from the pulse regenerator 13 isapplied through a lead 45 to grid 43 placing an enabling bias thereon. Apulse from the pulse regenerator 17 is applied through a lead 46 to thegrid 42 placing a disabling bias thereon. Under these conditions, ifpulses are applied in coincidence upon the grids 42 and 43, no pulse istransmitted through the gate, but if a pulse is applied to grid 43 whenno pulse is applied to grid 42, the enabling bias on grid 43 enables apulse to pass, this pulse appearing at the output lead 47. There istherefore produced and impressed upon the output pulse counter 19 inFig. 3 one pulse for each missing or substandard pulse of the outputpulse train from the oscillator 10 under test. In Fig. 3, the inputpulse train or train of triggering pulses is impressed also directlyupon the input pulse counter 20. In this case the counters 19 and 20 areboth arranged to count forward, counter 19 registering missing andsubstandard pulses and counter 20 registering all triggering pulses. Y

Fig. 9 shows an arrangement of conventional decimal counting unitssuitable for use in a forward counting pulse counter such as the inputpulse counter 20 in Figs. l, 2, and 3 and the output counter 19 whenused with the anticoincidence gate 23 in Fig. 3. Any desired number ofdecimal counting units may be employed. These units may be of any knowntype which can be operated by electric pulses such as those suppliedvbythe pulse regenerators 17 and 18 or the gate 23. Byway of illustration,six decimal counting units are shown, schematically, giving a countingcapacity of 999,999. The units are designated 48 through 53, beginningwith the units counter 48 and ending with the hundred-thousands counter53. Pulses entering vthe device of Fig. 9 from the right through aninput lead 54 operate the-units counter 48 successively from 0 to-,9andv upon the arrival .ofV the tenth pulsekthe units counter ,43 isreturned ,to

and the tens counter t9-is advanced to 1, in well known manner vcommonto counting devices in general. An initial reading of 000,000 is shownschematically by lights illuminating the corresponding digits on therespective counters. Lead 55 represents an output lead arranged toproduce a signal, suc-h as a stop signal for controlling the outputpulse counter 19 to stop the latter when an input pulse count of 100,000has been reached. Alternatively, an output lead such-as lead 55, or asuitable set of output leads, maybe arranged to be energized at a totalinput count of any integral power of l() within the range of the counteror at any number in between such powers of 10.

Fig. 10 shows 'how the scales on the various counters of Fig. 9 can beinverted to provide a backward counting pulse counter :for -use asoutput pulse counter 19 in the arrangements of Figs. 1 and 2. The scalesof all the counters are simply changed to read from 9 back to 0 instead`ofrfrorn 'O'forwa-rd to 9, each digit being replaced -by the differencebetween that ydigit and 9. The register in Fig. l0 is shown with -aninitial reading of 1100,000 exhibited. rlhis is equivalent to settingthe counters of Pig. 9 -to 'an initial reading of 899,999. It will beevident that the application of 100,000 successive pulses Itothearrangement-of Fig. 10 will produce a inal reading of 000,000 which 'isequivalent to a reading lof V999,999 in the arrangement of Fig. 9. Thatthe arrangementof Fig. VlO-willcount backward will be evident froman-example, wherein 99,500 pulses are applied to the arrangement of Fig.l0, thereby advancing the count from 899,999 to 999,499 -in terms ofthearrangement of digits 'on the counters in Fig. -9. The number 999,499 inthe lnormal arrangement, Fig. 9, vcorresponds vto the number 000,500 inthe inverted arrangement of Fig. l0, thereby registering the correctnumber of missing pulses, namely 100,000 minus 99,500, or 500 missingpulses.

Fig. -ll shows details of -a calibrator suitable for use as calibrator24oflFivg. 1 and'arranged, for example, to provide a VCalibratingcondition of one missing pulse for each twenty Vtriggering pulses. Afree-running multivibrator 56 lis utilized to supply triggering pulsesin place of-thoseobtained-in ordinary use from the pulser 11, and alsoto produce-trains of 19 pulses followed by a missing pulse interval.Pulses 'from the multivibrator 56 are applied to counter 57 toladvanceit-from 0 to-9. The tenth and following pulses pass through alead 59 to advance the counter 58 from Olto 9. Here the connectionsbetween the counter -57 and-58 differ from the connections between unitcounter-'48 and Atens counter 49 of Fig. 9. r[he twentieth pulse passesthrough a lead 60to one of the control grids of agate 6'1. All pulsesare applied successively to the second control gridof the gate61. Thegate 61 is arranged for anticoincidencefpassing apulse except whenpulses are applied simultaneously to both control grids.

As-thusarranged, l19 pulses pass through and the twentieth pulse-isblocked "by the gate 61. The twentieth is also employed to resetcounters 57 and 58 each tozero. Other patterns of pulses and misses mayreadily be arranged in the calibrator 24 as will be evident to thoseskilled in the art.

"With-the-calibrator 24 -set for any desired proportion of missingpulses, with'the switch 25 in the downward position land the switch 26Vinthe upward position, the system of Figs. l, 2, or 3J may be checkedfor accuracy. Assuming-thatfthe calibrator is set up to supply percentVmissing pulses, for example, and Va trial measurement `using100,000ftriggeringpulses is-made in the system of "Fig, 1 orFig.3,'theresult-should be 5000 missing pulses. 'In the-'system'offFig 2, theratio of missing pulses to total triggeringpulses should bel exactlyV5-to 100. Anydeparture from vthe-expected result will be indicativelofimproperoperationfof the Vportion ofthe system tested.

The gate S1-may bev-adjusted-lto passall pulses but to lreduce'tltteheight ofthetwentieth'pulse to'any desired Two units counters 57 and 58are used.

part of `the normal height. For example, the twentieth pulse may bereduced to 70 percent of normal height. In this case if the comparator16 is set to select a 70 percent level, that is, to be unresponsive toany pulse that does not exceed percent, then the twentieth pulse will becounted as missing. The level selector adjustment of the potentiometerarm 3S when suitably calibrated may be used in setting the gate 61 toreduce the twentieth pulse to the proper amount so that it will justfail to be selected and will therefore be counted as missing.

When adjusted to a given percentage height in the level selector, thesystems of Figs. 1, 2, and 3 will count as missing all pulses that arebelow the selected percentage height.

VIt is to be understood that the above-described arrangements areillustrative of the principles of the invention. Numerous otherarrangements may be devised by those skilled in the art withoutdeparting from the spirit and scope of the invention.

What is claimed is: Y

1. A direct-reading system for indicating the percentage of failures ofa given device in response to a plurality of excitations of the givendevice, comprising means to excite the given device repetitively, meansto count the individual excitations of the given device, means actuatedbyrindividual responses of the given device to display one by one aseries of indicia representing the cardinal numbers in descending orderfrom a given integral power of ten down to zero inclusive, means tostart the said counting means and the said display means substantiallysimultaneously, and means actuated by said counting means toY stop thesaid display means at the end of a number of excitations of the -givendevice equal to -the said given integral power of ten.

2. A direct-reading system for indicating the percentage of substandardresponses of a given device, comprising selective means connected to theoutput circuit of the given device to discriminate against substandardresponses thereof, means actuated by such responses of the given deviceas are accepted by said selective means to display one by one a seriesofindicia representing the cardinal numbers in descending order from agiven integral power of ten down to zero inclusive, means to excite thegiven device repetitively, means to count the individual excitations ofthe given device, means to start the said display means and the saidcounting means simultaneously, and means to stop the said display meansat the end of a number of excitations of the given device equal to thesaid given integral power of ten.

3. A direct-reading system for indicating the percentage of substandardresponses `of a given device, comprising pulse generating discriminatorymeans connected to the output of the given device to discriminateagainst substandard responses of the given device, said means producinga pulse for each passable response of the given device, pulse actuatedmeans to display one by one a series of indicia representing thecardinal numbers in descending order from a given integral power of tendown to zeroinclusive, said-last-mentioned means being connected-to thesaid pulse generating means, means to excite the given devicerepetitively, -means to count the individual excitations of the givendevice, means to start the said excitation counting means and the saidnumerical display means-simultaneously, and means to stop-the saiddisplay means at the end of a number of excitations of the given deviceVequal to the said given integral power of ten.

4. .A system for determining the percentage of'missing output pulsesfrom a pulse source in response to a train of input pulsess comprising apulse counter connected to the input circuit of the pulse source, meansactuated by individual output pulses from the pulse source to displayone by one a series of indicia representing the cardinal numbers indescending order from a given integral power of vten Ydown to zeroinclusive, means to start the said coun-ter and the said display meanssubstantially simultaneously, and means actuated by said counter ltostop the said display means when the counter has registered a number ofinput pulses equal to the given integral power of ten.

5. A system for indicating the number of responses of a given device toa given number N of excitations of the device, comprising means toexcite the given device repetitively, means to count the individualexcitations of the given device, means actuated by individual responses`of the given device to display one by one a series of indiciarepresenting the cardinal numbers in descending order from N to zeroinclusive, means to start the said counting means and the said displaymeans substantially simultaneously, and means actuated by said countingmeans to stop the said display means at the end of N excitations of thegiven device.

6. A system for indicating the number of substandard responses of agiven device to a given number N of excitations of the device,comprising selective means connected to the output circuit of the givendevice to discriminate against substandard responses thereof, meansactuated by such responses of the given device as are accepted by saidselective means to display one by one a series of indicia representingthe cardinal numbers in descending order from N to zero inclusive, meansto excite the given device repetitively, means to count the individualexcitations of the given device, and means actuated by said countingmeans to stop said display means at the end of N excitations of thegiven device.

7. A system for indicating the number of substandard responses of agiven device to a given number N of excitations of the device,comprising pulse generating discriminatory means connected to the outputof the given device to discriminate against substandard responses of thegiven device, said means producing a pulse for each acceptable responselof the given device, pulse actuated means to display one by one aseries of indicia representing the cardinal numbers in descendingnumerical order from N to zero inclusive, said last-mentioned meansbeing connected to the said pulse generating means, means to excite thegiven device repetitively, means to count individual excitations of thegiven device, and means actuated by said counting means to `stop saiddisplay means at the end of N excitations of the given device.

8. A system for measuring the proportionate number of responses of agiven device with respect to the number of excitations of the givendevice, comprising means to excite the given device repetitively, meansto count the individual excitations of the given device, means to countresponses of the given device, means to start said counting meanssubstantially simultaneously, and means to stop said counting meanssusbtantially simultaneously.

9. A system for determining the proportionate number of substandardresponses of .a given device with respect to the number of excitationsof the given device, comprising selective means connected to the outputcircuit of the given device to discriminate against substandardresponses thereof, means to count responses of the given device acceptedby said selective means, means to excite the given device repetitively,means to count the individual excitations of the given device, means tostart both vsaid counting means simultaneously, and means to stop bothsaid counting means simultaneously.

10. A system raccording to claim 9 `in which the selective means isfrequency selective for rejecting responses of nonstandard frequency.

1l. A system in accordance with claim 9 in which the lselective meanscomprises power integrating and comparing means for rejecting responsesbelow a selected power level.

l2. A system according to claim 9 in which the selective means comprisesfrequency selective means for rejecting responses of nonstandardfrequency and power integrating and comparing means for rejectingresponses below a selected power level.

13. A system for determining the proportionate number of substandardresponses of a given device with respect to the number of excitations ofthe given device, comprising pulse generating discriminatory meansconnected to the output of the given device to discriminate againstsubstandard responses of the given device, Asaid means producing a pulsefor each acceptable response of the given device, means to count pulsesthus produced, means to excite the given device repetitively, means tocount individual excitations .of the given device, means to start bothsaid counting means simultaneously, and means to stop both said countingmeans simultaneously.

14. Device testing means comprising a source yof electrical pulses,means for app-lying pulses from said Asource to a device to be tested,pulse translating means, means for also applying pulses from said sourceto said pulse translating means and means for comparing the number ofyoutput pulses delivered, respectively, by said device under test andsaid pulse translating means.

l5. Means for monitoring the operation of an electrical devicecomprising, a source of electrical pulses, means for applying pulsesfrom said source to said device, means for extracting output pulses fromsaid device, comparison means having two inputs for determining therelative occurrence of pulses applied to said two inputs, means forapplying pulses from said source to one of said two inputs, means forapplying said output pulses to the other of said two inputs and meansfor converting the pulses applied to said two inputs into waveforms offsubstantially identical shape.

16. Apparatus for measuring the performance characteristics of anelectrical device comprising a source of electrical pulses, a iirstcircuit having an input and an output, said iirst circuit including saiddevice and having its input connected to receive pulses from saidsource, means in said first circuit for adjusting the amplitude of theoutput pulses delivered by said device, a second circuit having an inputand output, said second circuit also having its input connected toreceive pulses from said source and means for comparing the number ofpulses occurring at the output of said rst circuit with the number ofpulses occurring at the output of said second circuit.

17. Apparatus for indicating the number of pulses that are missing fromthe output of a pulsed magnetron with respect to the number of inputpulses applied thereto comprising, a source of pulses, means forapplying pulses from said source to pulse said magnetron, an outputcircuit for receiving pulses from the output of said magnetron,comparison means having two inputs for deriving an indication of thedilerence in the number of pulses applied to said two inputs, means forapplying pulses from the output of said magnetron to one of said inputs,and means for applying pulses from said source equal in number to thepulses applied to said magnetron to the other of said inputs.

18. Apparatus for determining the pulse transmission characteristics ofan electrical device comprising, a source of electrical pulses, meansfor applying pulses from said source to the input of said device, firstpulse translation means connected to receive pulses from the output ofsaid device and for deriving a first pulse wave train, second pulsetranslation means connected to receive the same number of pulses fromsaid source as are applied to said device and for deriving a secondpulse wave train, and comparison means connected to receive said firstand second pulse wave trains, said comparison means comprising means forindicating the percentage of pulses in said second train for which thereare no corresponding pulses in said first train.

19. The combination in accordance With claim 18 wherein said secondpulse translation means comprises means for deriving a train of pulsessimilar in wave shape and amplitude to the pulses of said first pulsewave train.

Y I1 20: The. method of? testinga pulse generator. which comprises;applying electfical;l pulses: to said generator,

shaping: the output pulses ofi-'said generator, deriving a:

cation Qf; the numberof' output pulses missing from saidgenerator withrespectV tothe number of pulses; applied References Citedfjinthe filelof thisl patentV Mumma Jly 9, 19,46v Grosdo July 16,l 1946 Pyatt` etYal. Sept. 27, 1949 MacSorley Iune.26,'151` McMillan Oct. 20, 1953V...m-w *n EN* Nuff

